Guest essay by Eric Worrall
US based SpinLaunch has performed their first 20% power launch, flinging a test payload “10s of thousands” of feet into the sky.
Alternative rocket builder SpinLaunch completes first test flight
PUBLISHED TUE, NOV 9 20211:19 PM ESTUPDATED TUE, NOV 9 20214:25 PM EST
Michael Sheetz@THESHEETZTWEETZSpinLaunch, which is building an alternative method of launching spacecraft to orbit, last month conducted its first test flight of a prototype in New Mexico.
The company is developing a launch system that uses kinetic energy as its primary method to get off the ground – with a vacuum-sealed centrifuge spinning the rocket at several times the speed of sound before releasing.
…
“It’s a radically different way to accelerate projectiles and launch vehicles to hypersonic speeds using a ground-based system,” SpinLaunch CEO Jonathan Yaney told CNBC. “This is about building a company and a space launch system that is going to enter into the commercial markets with a very high cadence and launch at the lowest cost in the industry.”
…
The SpinLaunch suborbital accelerator represents a one-third scale version, but – standing about 165 feet, “taller than the Statue of Liberty” – Yaney emphasized that it’s the size the company needs “to really prove the technology.”
The vacuum chamber holds a rotating arm, which Yaney said accelerates the projectile to high speed and then, “in less than a millisecond,” releases the vehicle for launch. The suborbital projectile is about 10 feet long, but “goes as fast as the orbital system needs, which is many thousands of miles an hour,” Yaney added.
“We can essentially validate our aerodynamic models for what our orbital launch vehicles are going to be like and it allows us to try out new technologies when it comes to release mechanisms,” Yaney said.
SpinLaunch’s first suborbital flight utilized about 20% of the accelerator’s full power capacity for the launch, and reached a test altitude “in the tens of thousands of feet,” according to Yaney.
…
Read More: https://www.cnbc.com/2021/11/09/spinlaunch-completes-first-test-flight-of-alternative-rocket.html
A word of caution – SpinLaunch still have a long way to go, until they are ready to attempt their first true orbital launch.
So far that big carbon fibre arm has only been subject to 20% of its design tolerance. Pushing it to 100% or whatever the design velocity is will be a white knuckle ride. Any undetected mechanical flaw and the launcher could spectacularly disintegrate, with an energy release comparable to a rocket failure.
And like all ground based launchers, a course correction will be required once the payload is in space, otherwise the payload will come down on top of someone. Orbits mathematically tend to intersect the last point at which thrust was applied. So the launch vehicle will need a rocket or explosive charge which can survive the 10,000G initial launch to complete the orbital entry, to alter the trajectory once the payload is in space, to create a stable orbit which does not include re-entry into the atmosphere.
Before you dismiss this as impractical, consider that the extreme acceleration experienced by SpinLaunch payloads is comparable to the conditions experienced by an explosive smart projectile fired from a large artillery gun – so it is likely most of the technology required for the orbital insertion package has already been developed.
There will be plenty of uses for this launch system if they can get it working. Consumables like oxygen and prepared food can survive insane launch accelerations, so are obvious candidates for a high-G spin launch. Specially hardened satellites, even chunks of rock, to help transfer momentum to correct the orbit of large space stations, are all possible uses.
Even with a course correction component, SpinLaunch offers potentially enormous cost savings over a conventional launch. With conventional rocket launches, most of the mass of the launch vehicle is fuel. Think an enormous rocket with a tiny payload perched on top.
With SpinLaunch, only around half the mass of the launch payload will be fuel for the orbital insertion course correction, allowing far more useful payload to be lofted into space with each launch.
New and innovative technologies like SpinLaunch are a potential counter foreign space innovation efforts, like Russia’s nuclear powered launcher project, which if perfected could pose a significant challenge to US space dominance.
The following video provides more background on SpinLaunch.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
I strongly suspect that every penny that is saved on launch vehicles will be spent building a space craft that can stand the 10,000 G’s experienced during launch.
Another problem with these kinds of launch systems is that greatest velocity is seen at the same place where the atmosphere is the densest. Talk about your sonic booms.
Hmmm, just like the centrifugal pumpkin chuckers.
Current records for the centrifugal category:
“3245.58 ft”
That’s a pretty good toss!
It’s a danged amazing toss!
Bad to the Bone used a rusty old truck to power their centrifugal machine. The truck would rock and shake as the operator gunned the fuel pedal till the machine was in maximum spin.
Trying to exceed his own record the centrifugal arms broke. His attempts to rebuild the centrifuge kept failing as tried longer arms.
I haven’t seen him back.
The Smokin Lamas used human powered bicycles to achieve their throws with a centrifuge.
Many of the more powerful pumpkin chuckers suffered frequent disintegration of the pumpkin at launch. Counts as a failed throw attempt. Any weakness and the projectile breaks apart.
Finding volunteers to ride the rockets may be a problem…
And are we to assume spacecraft launched this way will be ball or football shaped?
I hate to throw a wet rag on this concept, but it really is totally impractical for getting payloads into near-Earth orbits.
Let’s say we want to get a spacecraft into a circular orbit, just outside most of Earth’s sensible atmosphere so that it might have a mission life of, say, one or two weeks before it decays to atmospheric reentry . . . we’re talking something around 160 km (100 statute miles) altitude.
For reference, the ISS has to have periodic orbital velocity boosting to maintain its nominal altitude against continuous atmospheric drag, even though it flies at about 400 km (250 statute miles) average altitude.
One can use one of several on-line calculators (e.g., https://keisan.casio.com/exec/system/1224665242 ) to find that a 160 km altitude circular orbit altitude requires an orbital velocity of 7,810 m/s.
So, for a 160 km circular orbit, the kinetic energy per kilogram of vehicle will be 0.5*m*v^2 = 0.5*1*(7,810)^2 = 30.5 MJ, where MJ is mega-joules.
Now let’s compare that necessary kinetic energy with the necessary potential energy that is associated with just vertically raising a kilogram of mass to the altitude of 160 km above Earth’s surface. This is the only energy that the SpinLaunch system can provide with a vertical launch.
The potential energy required to raise mass vertically in a gravitational field is ~m*g*(delta-h), neglecting the slight decrease in gravity over the relatively small delta-h vertical distance. On a per kilogram basis, the associated potential energy would be ~1*9.8*160,000 = 1.57 MJ.
These simple calculations show that SpinLaunch system provides energy that is only 1.57/(1.57+30.5) = 4.9% of that needed for putting a payload/vehicle into a 160 km circular orbit around Earth. The conclusion, of course, is that any projectile launched using the SpinLaunch system has to provide at least 95% of the energy it would need if just launched from Earth’s surface using standard rocket technology.
And that 5% energy savings from a SpinLaunch comes at a heavy price (pardon the pun) . . . all of the vehicle structure, avionics, propulsion system and payload must be designed to withstand the 10,000 g launch forces cited in the above article. To put that in perspective, almost every rocket launch system for putting payloads into space limits peak sustained acceleration forces to less than 30 g’s.
Yes, in the above I have neglected the energy losses associated with hypersonic vehicle flight (aerodynamic drag) through the lower portion of Earth’s atmosphere, and I have not cared to discuss the enormous problems of aerothermal heating associated with such flight, both of which are maximized in the SpinLaunch concept.
So, bottom line, SpinLaunch might eventually find limited use for suborbital, near-vertical launches to 150-200 km altitude, but forget about it being enabling for orbital missions.
The next SpinLaunch prototype won’t be vertical, the plan is for SpinLaunch to contribute to horizontal velocity. So if everything works out it will be capable of supplying a much large portion of the energy required to achieve a stable orbit.
Gerald Bull, arguably the greatest artillery genius of the 20th century, thought it could be done..
Yeah, I saw that in watching the video that was linked in your article (thank you for including that, BTW). Problem with going on a projectile path that is not vertical is that you extend the time-of-hypersonic flight in the atmosphere due to the resulting “slant range”, increasing the issue of managing aerodynamic heating and aerodynamic stability.
Next, there is the issue of orbital mechanics that says an object in an orbit, having no additional velocity increments, will return to same given orbital point within one orbital period (in the case of SpinLaunch, the projectile won’t have enough energy to even hit Earth on the “opposite” side in its parabolic ballistic arc, much less go completely around Earth to impact generally westward along the latitude of the SpinLaunch launch site.
Next, as I mentioned above, the orbital velocity needed for just a 160 km altitude circular orbit is 7,810 m/s. Assuming absolutely no aerodynamic drag and negligible energy to raise the projectile against gravity, that speed would be equivalent to Mach 22.8 at the launch . . . and NOBODY knows how to make a vehicle withstand heat loads or be dynamically stable in atmospheric flight at that speed.
Finally, the projectile, fired at ANY angle, will still need to provide its own velocity increment (via on-board propulsion system) to circularize the orbit (or at least to reduce its ellipticity so that perigee would be moved above Earth’s “sensible” atmosphere (e.g., > 200 km altitude).
Whether or not Gerald Bull knew the intricacies of orbital mechanics, I will not speculate.
That brings up the questions why and what, Eric.
Specifically, what could survive those G forces and still function after reaching orbit?
The answer is not much as we know right now. Unless they plan to launch solid projectiles like bombs. The Webb telescope certainly wouldn’t survive the trip.
A slightly different answer arises, if they only seek a way to launch supplies into orbit for pickup by the space station or similar.
No, there is a much more serious issue to the “pickup” of cargo from a SpinLaunch projectile for supplying the ISS (or similar).
An orbital rendezvous (to enable a gentle transfer of cargo) necessarily requires the matching of orbits . . . to be totally correct, the matching of orbital ephemeris, for the SpinLaunch vehicle carrying the cargo and the vehicle that is to pickup the cargo. This will require: (a) a tremendous amount of propellant mass to decelerate a cargo vehicle that is orbiting connected to/alongside the ISS, and (b) a tremendous amount of propellant mass to then boost the cargo vehicle (with cargo) back into the ISS orbit and to perform rendezvous with ISS.
And this is assuming the SpinLaunch projectile first gets itself into a stable LEO orbit.
If one consider the projectile just being on a (non-orbital) ballistic arc, then the “orbit” matching and cargo transfer will have to been performed near apogee outside of Earth’s atmosphere and within 5 minutes or less to enable the cargo transfer ship enough time to add the boosting delta-V needed to prevent atmospheric reentry.
We’ll have to have a lot of water ice in space if we are going to do large-scale space development.
The current plan is to get it from the Moon.
If this, or another launch system proves cheap enough to operate, then we could get the water ice from the Earth.
Tom,
There are also plans to manufacture water in space by recovering residual propellants from LOX/LH2 upper stages that are placed into LEO or Moon orbit, and in turn running the boiloff oxygen and hydrogen through fuel cells to generate both electricity and pure water.
This approach would be more efficient and much more simple than having to travel to/descend into the Moon’s gravity well, only subsequently to have to launch out of that well (with TBD water/ice mass) to supply any manned space station, whether orbiting the Moon or Earth.
It was estimated that the Space Shuttle’s External Tank would still have 15 to 20 tons of propellants left in it after reaching orbit.
This was for a study done about taking the ET all the way into orbit along with the Space Shuttle.
Just so.
The problem is the minimal altitude that the Shuttle ET would be placed into. Under a normal STS launch, the ET reached perigee (the release point for the Orbiter) at about 113 km altitude, and did not have enough kinetic energy to complete even one orbit of Earth.
Even if addition propulsive impulse was added to circularize the ET orbit at this altitude, it would likely have reentered the atmosphere is a mere matter of days due to atmospheric drag.
To have placed the ET in a circular orbit equivalent to that of ISS would not have been possible unless an STS launch did NOT include boosting the Orbiter.
Then too, the ET was not designed to minimize boil-off of LH2 (such as the design of a LH2 storage dewar), so most of that residual propellant would have been vented off by time of rendezvous with ISS.
It will be a hell of a lot cheaper to use a rail gun on the moon to get such stuff into Earth orbit.
It is impossible to be on a Moon-Earth trajectory and also “enter” Earth orbit without delta-V being used to change orbital parameters.
That “stuff” the lunar railgun launches to Earth better be contained within a vehicle having a very accurate navigation system and a significant propulsion system for mid-course corrections and for breaking into Earth orbit.
The lower the angle, the more time is spent in the atmosphere and the more energy lost to drag.
There’s a huge difference between a cannon and this device.
I’d like to see that. Imagine flinging John Kerry into space!
Probably improve his facial structure.
10,000G
———-
Color me skeptical. The loads to reach orbit are similar to a space elevator.
The problem is similar to anchoring in deep water with a rode that is heavier than water. Eventually the weight exceeds the yield strengrh as depth increases.
That can be fixed with a broader base. Its load / square meter which matters, not total load per projectile.
The problem is the arm and the radius of the spin. I show in another post that a radius of 100 feet is approaching the limits for carbon fiber even before you attach a payload.
Before dismissing this concept, just take a look at the basics. Launch speed about 5000 mph…velocities of this magnitude in the lower atmosphere appear to be well studied, and tried. I was immediately concerned about the heat up upon exiting the device…but that appears to be well handled by materials and geometry. The 10k G is scary, but as noted, there are a lot of materials and operational mechanisms that can withstand this kind of force.
Their forte would seem to be rapid launch of relatively light payloads. Perhaps this is how Musk can get enough fuel up to his Mars bound spaceship….
If launch cycle time is short, then imagine launching 1000 identical payloads in a relatively short period of time.
It will be very interesting to see how this pans out….great to see folks actually trying these ostensibly unusual methods of orbital insertion…
I will look forward to seeing a cost analysis of orbital insertion vs full fuel on board systems.
I quite agree…I can’t do the maths to know if orbital speeds are obtainable so I leave that to the experts. However, great to see others prepared to risk their and their shareholders’ money to try out these new concepts. They might just get a win. Who ever thought rockets could land on an ocean barge and be reused up to 10 times… However, not sure I want to invest just yet! I’ll leave that to the brave and daring.
This device makes much more sense as a bunker buster. Armed with a tungsten penetrator and fired into a mountain from a few feet above the ground it would pulverize any nuclear weapons or labs within the mountain. Equally effective against nuclear silos.
Yes, but not exactly portable or mobile though…
And the time required to put this facility in place in a hostile territory would be . . .?
These devices could be placed into orbit as Reagans star wars solution to counter hypersonic missiles. Also Iran and N Korean weapons research killer. 15000 mph penetrator launched at point blank range.
Do they bail out with the money at 30% or 40%?
Winan steam gun used during the American civil war.
The arm is a problem
A carbon fiber rod more than 100 feet long will fail under its own weight at 10 kG.
A foot of carbon fiber 1 inch in section weighs 1 pound and has a yield strength of 500 kpsi.
A rotating carbon fiber rod at 10 kG has an average load on 5 kG and will weigh on average 5000 lbs per foot.
A rod 100 feet long has a force of 500 kpsi at the inner attachment. Maybe this can be solved by tapering. Increasing the fiber section towards the center of spin.
Probably not impossible. Make more sense in space launching two objects in opposite directions.
On earth filling with hydrogen might reduce cost as compared to pulling a vaccum in such a large structure.
So, maybe my physics is rusty, but why 10,000 Gs? If I add centripetal acceleration at 2G/second, then during the entire “spin up” phase, I’m only experiencing 2G of acceleration – even through my accumulated velocity is insanely high.
Then, when I’m released, I go from 2G to 0G – no more acceleration. I experience a -2G acceleration.
Am I thinking of this wrong? Or are they talking about 10,000 Stapps (jerk force – rate of change of acceleration)?
You thinking is wrong. There is centrifugal (mistakenly called “centripetal”) acceleration from forcing an object to remain on a curved path (e.g., remain attached to a spin arm as it rotates) and there is, separately, the tangential acceleration of the projectile as the rate of spin is increased, starting from zero.
(I will not go into the details of why there really is no such thing as centripetal acceleration, but instead there is such a thing as centripetal force that is needed to counteract centrifugal acceleration. Detailed explanation available on the Web.)
There IS a variable rate of spinning up that could add 2 g per second (the centrifugal acceleration scales a (RPM^2)*r, where r is the radial distance from the center of rotation), but in the case of SpinLaunch I believe they are talking about 2 g (not 2 g/second) in the tangential direction.
In any event, the final g’s reached in either direction will depend on the g/second rate TIMES THE NUMBER OF SECONDS IT IS APPLIED. Alternatively, one could simply state an object on the end of the spin arm experiences a constant tangential acceleration of 2 g (not 2g/sec), which is what you seem to be asking about, but this would say nothing about the centrifugal acceleration that is developed because the time of action is left undefined.
Also, please note that at any given RPM, the tangential rate of acceleration could be dropped to zero (this is, keeping the RPM at a constant value) but the centrifugal acceleration at that constant RPM would still exist.
The tangential acceleration will be near zero at the time of projectile release from the spinning arm (design maximum RPM is obtained) but just prior to release the projectile will be experiencing 10,000 g of centrifugal acceleration.
Latest News: SpinLaunch researchers invent efficient way to turn astronauts into peanut butter. Film at 11.
I’m dating myself so bad….does anyone watch the nightly News any more? Do they still say that or is it now “video at 11”?
Jokes aside, good luck to them at SpinLaunch.
Wheeeee! But I’m going to be really dizzy by the time I get into orbit.
Does not say how fast. Escape velocity is ~37,000 ft/sec (>30x SOS). It says 20% power, not sure if that implies 20% speed (is power/speed ration linear or x^2?)
I would say military use lobbing projectiles hundreds of miles may be more practical. But will it be “net zero”? That seems to be the military’s big concern these days.
If nothing else it will work great to hit enemy satellites.